Respiratory assistance apparatus

ABSTRACT

A respiratory assistance apparatus includes a conduit connecting a flow generator and an outlet. The conduit includes a venture formation. The apparatus further includes an oxygen inlet in fluid communication or selective fluid communication with an oxygen outlet. The oxygen outlet is directed into the conduit and toward a mouth of the venture formation. The flow generator provides a flow path for air to enter the conduit when the flow generator is not operating.

The present invention relates to oxygen respiratory therapy apparatus,and in particular, but not exclusively, to a high flow oxygenrespiratory therapy apparatus which, in one mode of operation, can beoperated independently of an external electricity source.

BACKGROUND TO THE INVENTION

Oxygen respiratory therapy is used when a patient is conscious and nolonger requires a ventilator, but still needs to be supplied with anabove ambient concentration of oxygen.

In high flow oxygen respiratory therapy, ambient air, to whichadditional oxygen has been added, is supplied to the patient at a flowrate which is higher than the average rate at which the patient isbreathing. The flow rate is intended to be around the same as themaximum instantaneous flow rate during inspiration.

Typically the apparatus used to supply the air/oxygen mixture to thepatient is powered by a mains power connection. The apparatus may alsoreceive oxygen from a static oxygen supply. These connections mean thatthe apparatus is essentially immobile when in use.

However, patients for whom this type of therapy is prescribed maybenefit from the ability to leave their bed and move around to somedegree, while still receiving oxygen enriched air.

It would also be advantageous if the apparatus could continue to supplythe patient with an enriched air supply even in the event of a powerfailure or a malfunction of the pump which is supplying the air.

The reference to any prior art in the specification is not, and shouldnot be taken as, an acknowledgement or any form of suggestion that theprior art forms part of the common general knowledge in any country.

It is an object of the present invention to provide an oxygenrespiratory therapy apparatus which will overcome or ameliorate problemswith such apparatus of the prior art, or at least one which will providea useful choice.

Other objects of the present invention may become apparent from thefollowing description, which is given by way of example only.

SUMMARY OF THE INVENTION

According to one aspect of the present invention there is provided arespiratory assistance apparatus comprising a conduit connecting a flowgenerator and an outlet, the conduit comprising a venturi formation, theapparatus further comprising an oxygen inlet in fluid communication orselective fluid communication with an oxygen outlet, the oxygen outletdirected into the conduit and toward a mouth of the venturi formation,wherein the flow generator provides a flow path for air to enter theconduit when the flow generator is not operating.

According to a second aspect of the present invention there is provideda respiratory assistance apparatus comprising a conduit connecting aflow generator and an outlet, the conduit comprising a venturiformation, the apparatus further comprising an oxygen inlet in fluidcommunication or selective fluid communication with an oxygen outlet,the oxygen outlet directed into the conduit and toward a mouth of theventure formation, wherein the flow generator provides a flow path ofair to enter the conduit when the flow generator is not operating, andwherein the apparatus comprises a humidifier between the venturiformation and the outlet.

Preferably, the oxygen outlet directs a jet of oxygen toward the centreof the mouth of the venturi when in use.

Preferably the apparatus comprises a second oxygen outlet in selectivefluid communication with the oxygen inlet.

Preferably the second oxygen outlet is provided at a throat of theventuri.

According to a third aspect of the present invention there is provided amethod of operating a respiratory assistance apparatus comprising,

in a first mode of operation, operating an flow generator to pump air toan outlet of the apparatus, and

in a second mode of operation, wherein the flow generator is notoperating, directing a jet of oxygen towards a venture formation,thereby drawing air through the flow generator and forming a combinedoxygen/air flow to the outlet of the apparatus.

Preferably the method further comprises the step of adding oxygen to theair when in the first mode of operation.

The invention may also be said broadly to consist in the parts, elementsand features referred to or indicated in the specification of theapplication, individually or collectively, in any or all combinations oftwo or more of said parts, elements or features, and where specificintegers are mentioned herein which have known equivalents in the art towhich the invention relates, such known equivalents are deemed to beincorporated herein as if individually set forth.

According to a further aspect there are provided respiratory assistanceapparatus and methods of operating respiratory assistance apparatus andmethods of operating respiratory assistance apparatus according to theattached claims.

According to a still further aspect of the present invention, a oxygenrespiratory therapy apparatus and/or a method of operating a oxygenrespiratory therapy apparatus is substantially as herein described, withreference to the accompanying drawing.

Further aspects of the invention, which should be considered in all itsnovel aspects, will become apparent from the following description givenby way of example of possible embodiments of the invention.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic drawing of an oxygen respiratory therapy apparatusof the present invention.

FIG. 2 is a schematic drawing of an oxygen respiratory therapy apparatusof the present invention with an optional second oxygen inlet.

FIG. 3 is a schematic drawing of the oxygen respiratory therapyapparatus of FIG. 1 connected to a humidification apparatus.

FIG. 4 is a schematic drawing of an oxygen respiratory therapy apparatusof the present invention with an integrated humidification apparatus.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to FIG. 1 , a respiratory assistance apparatus of the presentinvention is generally referenced by arrow 100.

The apparatus 100 comprises a flow generator 1. The flow generator 1typically comprises a fan or impeller that is rotatably driven by avariable speed motor, and can comprise a centrifugal pump. In preferredembodiments, the flow generator 1 can generate flow rates of at leastabout 5 litres per minute, or of at least about 10 litres per minute, orof at least about 15 litres per minute, or of at least about 20 litresper minute, or of at least about 25 litres per minute, or of at leastabout 30 litres per minute, or of at least about 35 litres per minute,or of at least about 40 litres per minute, or of at least about 45litres per minute, or of at least about 50 litres per minute, or of atleast about 60 litres per minute, or of at least about 70 litres perminute, or of at least about 80 litres per minute. In some embodiments,a filter 10 may be connected to the flow generator 1 such that incomingair may be filtered.

The flow generator 1 supplies air to an intake conduit 2.

The intake conduit 2 has an outlet 3 to which a patient interface (notshown) may be connected, typically via a further flexible conduit and/orfurther conditioning equipment. Any suitable patient interface may beused, for example nasal cannulas or nasal masks. In some embodiments,the patient interface can be selected from the group consisting of: anasal cannula, such as the OPTIFLOW nasal cannula manufactured by Fisher& Paykel Healthcare Limited of New Zealand; a nasal mask, such as theOPUS nasal pillows mask manufactured by Fisher & Paykel HealthcareLimited of New Zealand; a full-face mask, such as the FREEMOTIONfull-face mask manufactured by Fisher & Paykel Healthcare Limited of NewZealand; a tracheostomy interface, such as the DIRECTCONNECTtracheostomy interface manufactured by Fisher & Paykel HealthcareLimited of New Zealand.

The intake conduit 2 is provided with a venturi formation 4 locatedbetween the flow generator 1 and the outlet 3. The venturi formation 4has a mouth 5 at an upstream end (that is, fluidically connected to theflow generator 1).

The apparatus 100 has an oxygen inlet 7 which is in fluid communication,or at least selective fluid communication, with an oxygen supply 6. In apreferred embodiment, an adjustable flow controller 8, for example aneedle valve, is provided in the flow path between the oxygen supply 6and the oxygen inlet 7. In preferred embodiments, the adjustable flowcontroller 8 may be manually adjustable, but, as is described furtherbelow, in other embodiments it may be electronically adjustable.

The oxygen inlet 7 can be positioned and orientated towards the venturimouth 5, such that a jet of oxygen issuing, in use, from the inlet 7, isdirected into the venturi 4, preferably directly into the centre of theventuri mouth 5.

As will be appreciated by those skilled in the art, in use the jet ofoxygen issuing from the inlet 7 will tend to entrain air through theventuri 4. Accordingly, in some embodiments, a vent or the like may beprovided near the venturi mouth 5 to provide a source of ambient air tobe entrained. In preferred embodiments, the flow generator 1 is adaptedto allow air to be entrained there through.

In a preferred embodiment the apparatus 100 is mountable to, orcomprises, a wheeled chassis.

The apparatus 100 may be used in two modes.

In a first mode, the flow generator 1 is powered by a mains powerconnection and pumps ambient air into the intake conduit 2. The pressureand/or flow rate of the ambient air supplied by the flow generator 1 maybe adjusted depending on the patient's requirements, but may typicallybe in the range 0-100 litres/minute, such as about 10 litres per minute,or about 15 litres per minute, or about 20 litres per minute, or about25 litres per minute, or about 30 litres per minute, or about 35 litresper minute, or about 40 litres per minute, or about 45 litres perminute, or about 50 litres per minute, or about 60 litres per minute, orabout 70 litres per minute, or about 80 litres per minute, and at apressure of between 0-50 cm H₂O, such as about 5 cm H₂O, or about 10 cmH₂O, or about 15 cm H₂O, or about 20 cm H₂O, or about 25 cm H₂O, orabout 30 cm H₂O, or about 35 cm H₂O, or about 40 cm H₂O, or about 45 cmH₂O, or about 50 cm H₂O.

The oxygen supply 6 is connected to a pressurised oxygen source, forexample a centralised oxygen supply or an oxygen bottle. The flow rateof oxygen from the oxygen supply 6 may be adjusted to suit the patient'srequirements, but will typically be such that the oxygen comprisesbetween 21% and 100% of the total volume of gas supplied to the patient.

In a second mode, the flow generator 1 is not operational. This may be aresult of a fault in the pump, a loss of mains power, or because thepatient wishes to move the apparatus 100 away from the bed, such that itis not possible or not desirable to have the apparatus 100 connected tothe mains power.

In the second mode, the oxygen flowing from the inlet 7 into the venturi4 creates an area of below ambient pressure which draws ambient airthrough the flow generator 1. The flow generator 1 may be configured tominimise the resistance to the ambient air flow in this mode ofoperation, and may comprise an impeller which offers relatively lowresistance to air flow between the pump inlet and outlet whenstationary.

If the patient desires to move around then the oxygen supply 6 may beconnected to a bottle of pressurised oxygen which, in a preferredembodiment, may be mounted to the apparatus 100. In this way the patientcan receive a source of oxygen enriched air while moving around. Thismay be beneficial in encouraging the patient to maintain or regainmobility after a period of enforced bed rest.

In some embodiments, the apparatus 100 can be provided with a controller11 which can be in communication with one or more sensors 12. Thesensors 12 can include: one or more pressure sensors; one or more flowrate sensors; one or more temperature sensors; one or more oxygenconcentration sensors.

In some embodiments, the apparatus 100 can also include a display unit13 on the apparatus. The display unit 13 can be adapted to showmeasurements from one or more of the sensors 12. Additionally oralternatively, the measurements can be communicated to a remotemonitoring station using known wired or wireless communications methods.

A portable power source 14, such as a battery, may be provided to enablethe sensors 12 and/or display unit 13 to function, or at least togenerate alerts or alarms, when the apparatus 100 is disconnected fromthe mains. The size and capacity of the portable power source 14 can bemuch smaller than would be required to power the pump 1 for asubstantial length of time.

If the flow generator 1 ceases operating unexpectedly then thecontroller 11 may sound an alarm to alert the patient and/or medicalstaff. However, the patient will still be supplied with a flow of oxygenenriched air. Although the flow rate of oxygen through the inlet 7 (andhence the flow rate of oxygen enriched air) may be increased if desired,this may not be required in some cases.

Those skilled in the art will appreciate that if apparatus 100 has onlya single oxygen inlet 7 then the range of oxygen enrichment in the airsupplied to the patient when in the second mode of operation will berelatively limited. However, in an alternative embodiment the apparatus100 may be provided with a second oxygen inlet 9. The second inlet 9 maybe provided upstream of the venturi 4, but is preferably not orientateddirectly towards the mouth 5 of the venturi 4, so that a flow of oxygenthrough the second oxygen inlet 9 does not cause a correspondingincrease in the flow rate of the ambient air. In a preferred embodimentthe second oxygen inlet 9 is directed substantially orthogonally to thedirection of air flow in its immediate vicinity, and more preferably isprovided in the wall of the venturi 4 at the throat.

When in the second mode, oxygen flowing through the second inlet 9 canbe used to increase the concentration of oxygen in the combined flowsupplied to the patient.

Referring next to FIG. 3 , in a preferred embodiment the apparatus 100is connectable to a humidification apparatus 15. An exemplaryhumidification apparatus 15 is described in U.S. Pat. No. 6,349,722, thecontents of which are included herein in their entirety by reference. Insome embodiments, the humidification apparatus 15 can be one of theMR810, MR850, MR880 humidifiers, all manufactured by Fisher & PaykelHealthcare Limited of New Zealand.

The humidification apparatus 15 preferably comprises a chamber 16 whichholds a volume of humidification fluid 18 (which can be water). Thechamber 16 can be formed of a plastic material, and will preferably havea thermally conductive base 17 (such as a metal base) connected thereto.The chamber 16 can be thermally coupled to a heater 19, which, in use,heats the humidification fluid 18 within the chamber 16 to increase itsrate of evaporation.

The chamber has an inlet 20 which is connectable to the outlet 3 ofconduit 2, and an outlet 21 which is connectable to a patient interface,typically via a flexible conduit 22. In preferred embodiments, theconduit 22 comprises an integral heating means to reduce the risk ofcondensation in the conduit 22. The heating means is typically a heaterwire 23. The heater wire 23 can be disposed within the gas path of theconduit 22, can be located within the wall of the conduit 22, can bewrapped helically around the outside of the conduit 22, and/or any othersuitable means as is known in the art.

A controller controls the heat input into the humidification fluid 18from the heater 19, in order to generate a required level of humidity inthe gases stream at the outlet 21. In a preferred embodiment thecontroller 11 may be adapted to communicate with and/or control thehumidification apparatus 15. The communication may be by any suitablewireless protocol, or there may be a wired connection between thehumidification apparatus 15 and the oxygen respiratory therapy apparatuscontroller 11. In one embodiment the humidification inlet 20 and theoutlet 3 may be provided with respective complementary sockets andplugs, so that an electrical connection is established between thecontroller 11 and the humidification apparatus 15 at the same time asthe gases flow path is established between them.

Referring next to FIG. 4 , in another embodiment, generally referenced101, the apparatus 100 and the humidification apparatus 15 may beincorporated into a single integrated unit. In this embodiment theportable power source 14 (not shown in FIG. 4 ), if provided, may alsopower the heater 19 for a period of time if the mains power source isinterrupted for any reason. In some embodiments the controller 11 mayallow the humidity at the outlet 21 and/or the temperature of the gas atthe outlet 21 to drop to a lower level if the mains power isinterrupted, so that the power consumed by the heater 19 is reduced. Theheater wire 23 may also be powered when the mains power is interrupted,although possibly at a lower power level. However, if the controllerlowers the humidity of the gas leaving the humidification apparatus 15then, depending on the ambient temperature, it may not be necessary topower the heater wire at all. In such a case the controller may switchoff the power to the heater wire in order to conserve power.

Unless the context clearly requires otherwise, throughout thedescription and the claims, the words “comprise”, “comprising”, and thelike, are to be construed in an inclusive sense as opposed to anexclusive or exhaustive sense, that is to say, in the sense of“including, but not limited to”.

Where in the foregoing description, reference has been made to specificcomponents or integers of the invention having known equivalents, thensuch equivalents are herein incorporated as if individually set forth.

Although this invention has been described by way of example and withreference to possible embodiments thereof, it is to be understood thatmodifications or improvements may be made thereto without departing fromthe spirit or scope of the invention.

The invention claimed is:
 1. A respiratory assistance apparatuscomprising: a flow generator; a conduit connected to the flow generator,the conduit comprising: a venturi formation positioned downstream of theflow generator; and an outlet, a first oxygen inlet in fluidcommunication or selective fluid communication with an oxygen supply,the first oxygen inlet directed into the conduit and directed toward amouth of the venturi formation; and an integrated humidifier comprisinga chamber, the chamber comprising an inlet and an outlet, wherein theinlet of the humidifier is connected to the outlet of the conduit;wherein the flow generator is configured to operate in a first mode anda second mode; wherein, in the first mode, the flow generator isoperational and pumps air through a flow path through the flow generatorto the conduit; and wherein, in the second mode, the flow generator isdeactivated and offers the flow path for air to enter the conduit whendrawn in from a pressure drop caused by oxygen flowing into the venturiformation.
 2. The respiratory assistance apparatus of claim 1, whereinthe first oxygen inlet is configured to direct a jet of oxygen towardthe center of the venturi formation.
 3. The respiratory assistanceapparatus of claim 1, further comprising a second oxygen inletconfigured to direct oxygen into the conduit.
 4. The respiratoryassistance apparatus of claim 3, wherein the second oxygen inlet isprovided upstream of the venturi formation but is not oriented to directflow directly towards the mouth of the venturi formation.
 5. Therespiratory assistance apparatus of claim 3, wherein the second oxygeninlet is directed into the conduit at a throat of the venturi formation.6. The respiratory assistance apparatus of claim 1, further comprisingan adjustable flow controller disposed between the oxygen supply and thefirst oxygen inlet.
 7. The respiratory assistance apparatus of claim 1,further comprising one or more sensors.
 8. The respiratory assistanceapparatus of claim 7, wherein measurements from the one or more sensorsare communicated to a remote monitoring station.
 9. The respiratoryassistance apparatus of claim 7, further comprising a controller incommunication with the one or more sensors.
 10. The respiratoryassistance apparatus of claim 7, further comprising a display unitconfigured to show measurements from the one or more sensors.
 11. Therespiratory assistance apparatus of claim 7, further comprising aportable power source configured to provide power to the one or moresensors.
 12. The respiratory assistance apparatus of claim 1, furthercomprising a portable power source.
 13. The respiratory assistanceapparatus of claim 12, wherein when a mains power is interrupted and therespiratory assistance apparatus is powered by the portable powersource, a humidity and/or a temperature of gas at the outlet of thechamber is dropped to a lower level.
 14. The respiratory assistanceapparatus of claim 12, wherein when a mains power is interrupted and therespiratory assistance apparatus is powered by the portable powersource, power provided to a heating element of the respiratoryassistance apparatus is reduced or disabled.
 15. The respiratoryassistance apparatus of claim 12, wherein the portable power sourceprovides power to a display unit.
 16. The respiratory assistanceapparatus of claim 12, wherein the portable power source provides powerto the humidifier and/or the flow generator.
 17. The respiratoryassistance apparatus of claim 1, wherein the respiratory assistanceapparatus is configured to generate an alert when the respiratoryassistance apparatus is disconnected from a main power source or theflow generator ceases operation.
 18. The respiratory assistanceapparatus of claim 1, wherein the respiratory assistance apparatus isconfigured to generate an alert when the flow generator unexpectedlyceases operation.
 19. The respiratory assistance apparatus of claim 1,wherein when the flow generator is not operating, the flow generatorprovides a flow path for air to enter the conduit.